render_to_string Messes Up assert_template

Recently, I ran into a situation where I wanted to have controller specific information in the layout. The easiest solution I came up with was to use the render_to_string method to set the content in a filter, like so:

  before_filter :set_infobar_content

  protected
    def set_infobar_content
      @infobar_content = render_to_string :partial => 'infobar_content'
    end

It was extra sweet because I just had to create a _infobar_content.html.erb view for each controller, and they’d all (magically) get their infobar content. Everything was fine until I ran my tests. That’s when I got this:

expecting <"index"> but rendering with <"_infobar_content">

Uh oh! I finally the solution in a ticket for Rails.

response.template.first_render = nil

Now my method looks like this:

    def set_infobar_content
      @infobar_content = render_to_string :partial => 'infobar_content'
      # The render_to_string method above screws up the assert_template methods
      # in the tests, so this is how we 'reset' it.
      response.template.first_render = nil
    end